How do trees decide when and where their branches grow?
In: Biology
DNA/genes. Their genetic code says to “be like a tree” and that means growing roots to absorb water and nutrients from the ground and to hold firmly in place, expanding the thickness of the trunk, and to reach up towards sunlight and produce a lot of leaves to absorb sunlight and carbon. Since it needs lots of leaves, it needs many branches. It’s pretty tough for DNA to code perfect symmetrical shapes and growth (like a perfect sphere or circle where the branches are *too* perfectly spaced) so it says to sort of grow for a while and then split a new branch “sometimes.”
This results in near-fractal-like structures, which is where the pattern of branch-smaller-branch repeats, but not at perfect intervals. That’s why most trees of the same type look similar but aren’t exactly the same. The branches split and new ones form at frequent, but imperfect intervals. This psuedo-randomness is actually quite pleasing to look at, like music: music has repeating patterns (like a chorus) but with small variations to prevent boredom. These patterns likely help attract all different kinds of life that the trees also need to thrive by spreading their seeds and nuts and fruits around and producing waste to enrich the soil.
Also, by somewhat randomizing the growth patterns, leaves can fill in more spaces and probably absorb the most sunlight this way by creating a more full canopy. Imagine sticking toothpicks into an apple, straight out from the center, and then extending those toothpick lines out for another foot. If tree branches grew straight out at perfectly spaced intervals, their branches would eventually spread away from each other and leaves wouldn’t cover as much area to soak up the sunlight. It also makes for less interesting places for animals to make their homes.
So they grow in a psuedo-random pattern, which is a lot like fractals with small variations. If you don’t know what fractals are then please check out a good YouTube video on them, it is beyond the scope of this question.
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